Fluid control system

ABSTRACT

A fluid control system for an elevating scraper incorporating a master control valve for selectively directing fluid to a floor gate cylinder and an ejector gate cylinder, and a pilot sequence valve for sequentially operating said master control valve to assure that fluid will be initially directed to the floor gate cylinder and then subsequently to the ejector gate cylinder; there being a fluid line connecting the floor gate cylinder and the pilot sequence valve for passage of fluid to the latter after the floor gate has been fully extended.

United States Patent 1191 Schantz 1451 May 22, 1973 s41 FLUID CONTROLSYSTEM 2,301,028 11/1942 Esch ..91/412 x 2,354,860 8/1944 Hartsock eta]. ..9l/4l2 X [751 memo scham' 2,682,150 6/1954 Ballinger...' ..60/97s12 [73] Assignee: Westinghouse Air Brake Company, I

Pittsburgh, p Primary Examiner-Edgar W. Geoghegan Attorney-Robert J. Eck[22] Filed: Aug. 25, 1971 21 Appl. No.: 174,595 ABSTRACT A fluid controlsystem for an elevating scraper incor- 52 U.S. c1. ..91/412, 37/124,251/28, 'P master control valve for Selectively direct- 60/421 ing fluidto a floor gate cylinder and an ejector gate 51 1111. C1. ..F15b 11/16Fi5b 13/09 cylinder and a Pilot sequem valve sequentially 58 Field 01Search ..91/412- 60/97 SE Wanting said master valve fluid 60/421 will beinitially directed to the floor gate cylinder and then subsequently tothe ejector gate cylinder; there being a fluid line connecting the floorgate cylinder [56] References Cited and the pilot sequence valve forpassage of fluid to the UNITED STATES PATENTS latter after the floorgate has been fully extended.

1,994,974 3/1935 Wiedmann ..91/4l2 X 6 Claims, 5 Drawing Figures [IIIPATENI 14:.Y22 1m SHEET 1 [IF 4 INVENTOR RONALD K. SCHANTZ 5% TaYPATENTEDWXZZISB sum 2 [1F 4 M l v 1 INVENTOR RONALD K. SCHANTZ &

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ill'llll' wk m PATEN IHJ 8, 733 964 SHEET 3 OF 4 |||IIII H iii fl II IIn we INVENTOR RONALD K. SCHANTZ w zy ATTORNEY PAIENTED R1122 ms SHEET U0F 4 INVENTOR RONALD K. SCHANTZ 1 FLUID CONTROL SYSTEM BACKGROUND ANDSUMMARY OF THE INVENTION The present invention relates in general to anelevating scraper, and more particularly, to a fluid control systemtherefor.

Heretofore it has been a practice in the elevating scraper art toprovide simultaneous introduction of fluid pressure to both the floorgate and the ejector gate cylinders, relying on the resistance of theload to create a sequential movement of said floor and ejector gates,such as shown and described in U.S. Letters Patent issued to 1.15.Hancock US. Pat. No. 3,066,429. Such simultaneous actuation of both thefloor gate and ejector gate cylinders was unacceptable to the industrybecause it developed inconsistent and variable results. Oftentimes afloor gate would freeze or bind thereby resulting in considerablepressure exerted by the ejector gate, causing great compaction andconducing to a more difficult unloading. Moreover, the ejector gatewould frequently force material through the elevatoror through the topof the earth collecting bowl, thereby causing damage to the elevator aswell as causing undesired spillage of the load.

By the present invention, the above disadvantages have been alleviatedas the floor gate cylinder and the ejector gate cylinder are trulysequential in operation; the ejector gate cylinder being precluded frommovement until the floor gate cylinder has been fully extended. By sodoing a substantial portion of the material in the bowl will be releasedthrough the floor opening prior to the movement of the ejector gatecylinder thereby requiring less initial pressure and enhancing the lifeof the ejector gate cylinder. In viewof the sequential operation of thefloor gate and ejector gate cylinders, there is no compaction problemsas above described nor is there any opportunity for the material in thebowl to be forced outwardly through the elevator or through the top ofthe bowl.

BRIEF DESCRIPTION OF THE DRAWINGS the pilot sequence valve and the flowcontrol system in a position for effecting simultaneous retraction ofthe floor gate and the ejector gate.

FIG. 5 is a vertical transverse section taken on the line 55 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawingswherein like reference characters designate like corresponding parts,there is shown in FIG. 1 an elevating scraper20, or other similar earthmoving vehicle, comprising a mobile tractor 21 having a frame 22 towhich is connected a yoke 23 extending rearwardly for connection to theframe 24 of an earth collecting bowl 25. The tractor 21 is provided withthe customary power or drive connection to the earth collecting bowl 25;and is also provided with a hydraulic ram cylinder 26 connecting theframe 22 of the tractor 21 with the frame 24 of the earth collectingbowl 25 for adjusting the'height of the latter above ground. Suitablymounted to the forward end portion of the frame 24 is an elevator 27,such as of the customary chain and paddle type, which operates in awellknown manner to scrape earth into the bowl 25. The rearward end offrame 24 is supported above ground by an axle 28 having its end portionsconnected to wheels 29.

Said earth collecting bowl 25 comprises a pair of spaced-apart sidewalls 30,30 which are integral at their lower edge portion with a flooror bottom wall 31; said bottom wall 31 having a forward edge 31'terminating spacedly rearwardly from the forward end portion of sidewalls 30,30. for developing an opening 32 within the earth collectingbowl 25. Presented in normally closing relationship with said opening 32is a floor gate 33 having its rearward edge 34 located spacedlyrearwardly of the forward edge 31 of bottom wall 31, when the floor gate33 is in fully retracted position as illustrated in FIG. 1. Formedintegral with the forward edge 35 of the floor gate 33 is a lug 36 whichis suitably connected to the outer end portion of a piston 37 of a fluidresponsive cylinder 38, of the doubleacting type, which is secured tothe frame 24.

Provided intermediate the side walls 30,30 transversely within saidearth collecting bowl 25, thereis provided an ejector gate 39 having awidth slightly less than the width between side walls 30,30 and a heightgreater than same. The lower end edge 40 of said ejector gate 39 is inengagement with a slide plate 41 being forwardly and downwardly inclinedand located upwardly of the bottom wall 31. The forward portion of saidslide plate 41 is formed integral with a depending skirt 42 whichengages the forward edge 31 of the bot? tom wall 31. Mounted on therearward face of said ejector gate 39 there is a thrust frame 43attached to the outer end of a piston 44 of a fluid responsive cylinder45, of the double-acting type, which is mounted to the frame 24. As willbe seen, the fluid responsive cylinders 38 and 45 operate to extend andretract the associ ated pistons 37 and 44, respectively, for moving thefloor gate 33 and the ejector 'gate 39, respectively.

Referring to FIG. 2, said fluid responsive cylinder 38 is formed withforward and rearward end walls 46,46 and an intervening side wall 47,said walls cooperating to define a compartment 48. Received withincompartment 48 is a piston head 49 which is connected to the' floor gateremote end portion of said piston 37, which latter projects outwardlyendwise through said rearward end wall 46'. Immediately adjacent saidrearward end wa1l46', the side wall 47 is provided with a port 50 whichis connected by a branch line 51 and a conduit 52 to a master controlvalve M, which will be described in detail hereinbelow. The forward endwall 46 of the fluid responsive cylinder 38 is furnished with a port 53which is connected by conduit 54 to the master control valve M. Providedwithin the side wall 47, spacedly downwardly from rearward end wall 46,there is a port 55 which is connected by conduit 56 to a pilot 'sequencevalve V, which will be described in detail hereinbelow. It will beobserved that said port 55 is spaced downwardly from the rearward endwall 46' a distance slightly greater'than that of the thicknessdimension of the piston head 49 when the latter is in engagement withthe rearward end wall 46 (FIG. 3).

Said fluid responsive cylinder 45 comprises forward and rearward endwalls 56,56 and an intervening side wall 57; said walls cooperating todefine a compartment 58 for slidably receiving a piston head 59 which isconnected to the ejector gate remote end portion of piston 44. Furnishedwithin the side wall 57 immediately adjacent the forward end wall 56 ofsaid fluid responsive cylinder 45 there is a port 60 which isconnectedby said branch line 51 and the conduit 52 to the master controlvalve M. It will be observed that both ports 50 and 60 of fluidresponsive cylinders 38 and 45 are connected in parallel by said branchline 51 so that fluid passing through conduit 52 will be equallydispersed to the respective compartments 48 and 58. Formed within therearward end wall 56' there is a port 61 which is connected by conduit62 to the master control valve M, as will be described.

MASTER CONTROL VALVE M Referring now to FIGS. 2-4 of the drawings, themaster control valve M comprises a pair of spaced-apart spool valves100,100 which are identical in every feature so that spool valve 100need only be described; it being understood that like elements of thespool valve 100' which correspond to the elements of the spool valve 100will be given like numerals to facilitate understanding and to avoidunnecessary repetitive explanation.

Spool valve 100 comprises a body 101 having a top wall 102, a bottomwall 103 and an intervening side wall 104. Extending longitudinallythrough said body 101 there is a bore 105 within which is received aspool 106 having opposed upper and lower end portions 107,108 and acentral valve portion 109, the latter being connected to the upper andlower end portions 107,108 by rods 110 and 111, respectively. The upperand lower end portions 107,108 are adapted to be moved axially inwardlyand outwardly of upper and lower fluid housings 112,113, respectively,which are conveniently mounted on the top and bottom walls 102, 103,respectively. Each fluid housing 112 and 113 is provided with aconventional resilient mechanism (not shown) for urging the spool 106into a predetermined, neutral position, which will be described.

The rods 110,111 are of a reduced diameter for cooperating with the wallof bore 105 and the spool 106 to define upper and lower fluid passages114 and 115, respectively. The central valve portion 109 is providedwith a groove 116, of relatively narrow extent, which is adapted tobe-presented in registering relationship with a passage 117 located inbody 101, said passage 1 17 being connected by a line 118 to theadjacnet valve body 101' of the spool 100'. Said groove 116 is incommunication (not shown) with a longitudinally disposed, relativelyenlarged recess 119 on the opposed side portion of the central valveportion 109, which recess 119 is adapted to effect selectivecommunication between ports 120,121, and 122 furnished within the body101. Said port 120 is connected by said conduit 52 to the branch line 51for communicating spool valve 100 with the ports 50 and 60 of the fluidresponsive cylinders 38 and 45, respectively; the port 121 by conduit123 to the discharge side of a pump 124, the intake side of which isconnected by a line 125 to a reservoir 126 containing hydraulic fluid;the port 122 by said conduit 54 to the port 53 of the fluid responsivecylinder 38 for communicating the spool valve therewith.

Downwardly of the port 122, the side wall 104 of body 101 is providedwith a return port 127 which is connected by return lines 128 and 129 tosaid reservoir 126. Said return port 127 opens into said lower fluidpassage and is in axial alignment with a port 130 of a fluid by-pass 131which is presented longitudinally within body 101 in axially parallelrelationship to bore 105. The other end portion of said fluid by-pass131 is connected to a port 132 which opens into the upper fluid passage114 of bore 105. Thus, it will be observed that the fluid by-pass 131maintains the upper and lower fluid passages 114 and 115 incommunication at all times.

The spool 106 of spool valve 100 is adapted for movement into threepositions; namely, a neutral position (FIG. 3), a gate extended position(FIG. 2), and a gate retracted position (FIG. 4). In the neutralposition, illustrated in FIG. 3, the valve central portion 109 ispositioned within bore 105 to block the ports and 122 and to establishcommunication between the conduit 123 and the passage 117 through therecess 119 and the groove 116 for directing fluid to said spool valve101'.

In the gate extended position (FIG. 2), the spool 106 is lowered forblocking the passage 117 and establishing communication between ports122,121 through recess 119; between ports 120 and 132 through the upperfluid passage 114; and between the port and the return port 127 throughthe lower fluid passage 115. Therefore, fluid will be directed fromreservoir 126 through the conduit 123, recess 119, conduit 54 to theport 53 for effecting extension of the piston 37; the fluid on theupward side of piston head 49 being returned through the port 50, branchline 51, conduit 52, upper fluid passage 114, by-pass 131, lower fluidpassage 115, and return lines 128 and 129 to the fluid reservoir 126.

In its gate retracted position (FIG. 4), the spool 106 is moved upwardlyof its neutral position for blocking the passage 117 and establishingcommunication between the ports 120 and 121 through recess 119; andbetween the port 122 and the return port 127 through the lower fluidpassage 115. Therefore, fluid from the reservoir 126 will be directedthrough conduit 123, recess 119, conduit 52, branch line 51 to the ports50 and 60 of fluid responsive cylinders 38,45, respectively, foreffective simultaneous retraction of the pistons 37 and 44,respectively. The fluid on the downward side of the piston head 49 ofthe fluid responsive cylinder 38 is re turned through port 53, conduit54, lower fluid passage 115, and return lines 128 and 129 to the fluidreservoir 126.

As noted hereinabove the elements of the spool valve 100' whichcorrespond identically to the spool valve 100 have been designated withlike numbers in FIG. 2. Therefore, said spool valve 100 comprises a body101 having ports 120'; 121', and 122' and a return port 127'; the port120' being connected by the conduit 133 to the conduit 52; the port 121'being connected to the line 118 for establishing communication betweenthe spool valves 100 and 100; the port 122 being connected by theconduit 62 to the port 61 of cylinder 45; and the return port 127' beingconnected by the return line 129 to the reservoir 126. The by-pass 131'of said valve body 101 is in communication through the ports 130' and132' to the upper and lower fluid passages 114' and 115', respectively,each of which are defined by the wall of bore 105' and the spool 106' inthe region of rods 110 and 111', respectively.

The spool 101' is also adapted to be axially moved into three positions;namely, a neutral position (FIG. 2), a gate extended position (FIG. 3),and a gate retracted position (FIG. 4). In the neutral position (FIG.2), said spool 106' is positioned so that said central valve portion109' blocks the ports 120 and 122 and establishes communication, throughthe recess 119' and the groove 1 16', between the line 118 and thepassage 117', which latter is connected by the line 134 to the returnline 129 for return flow to the reservoir 126. Thus, if both spools 106and 106' are in neutral position (not shown), fluid from the reservoir126 will be continuously circulated through the master control valve Mand returned thereto.

In its gate extended position (FIG. 3), said spool 106' is lowered forblocking the passage 117' and establishing communication between theports 121' and 122 through the recess 119' so that fluid passing throughthe line 118 will be directed through the conduit 62 to the port 61 ofsaid fluid responsive cylinder 45 for extending the piston 44.

Communication is also established between the ports 132 and 120' throughthe upper fluid passage 114' and between the port 130' and the returnport 127 through the lower fluid passage 115', so that fluid on theupper side of the piston head 59 will be directed through said branchline 51, conduits 52 and 133, by-pass 131, and return line 129 forreturn to the reservoir 126.

In the gate retracted position (FIG. 4) said spool 106 is raised so thatsaid central valve portion 109 blocks the passage 117 and establishescommunication between the ports 120 and 121' through recess 119' andbetween ports 122' and return port 127' through lower fluid passage115'. Thus, upon retraction of piston 44, fluid on the downward side ofthe piston head 59 will be directed through the conduit 62 and thereturn line 129 for return to said reservoir 126.

PILOT SEQUENCE VALVE V The upper fluid housing 112,112 of each spoolvalve 100, 100 is connected by lines 135,135, respectively, to the pilotsequence valve V comprising a body 200 having end walls 201,201connected by a side wall 202. Provided longitudinally through body 200is a bore 203 defining a valve chamber 204 which is connected with lines135,135 by ports 205,205, respectively, provided in the side wall of202. Diametrically opposed to ports 205,205 and axially therebetweenthere is provided in side wall 202 a feeder port 206 connecting thevalve chamber 204 through a pilot line 207 to a manual control valve C,which in turn is connected to a source of pilot fluid 208 as will bedescribed. Each end wall 201,201 is provided with a port 209 and 210,respectively, which are in axial alignment with the axis of the valvechamber 204. The port 210 is connected by the conduits 211 and 212 tothe manual control valve C; and port 209 by said conduit 56 to said port55 provided in the side wall 47 of the fluid responsive cylinder 38.Additionally, provided in communication with port 209 is a return line rwhich interconnects the port 209 with the pilot fluid reservoir 208 forrelieving the fluid pressure within the pilot sequence valve V.

Provided within valve chamber 204 there is a spool 213 comprising aforward portion 214, a rearward portion 215, and a diametrically reducedportion 216 therebetween. Located on either side of the diametricallyreduced portion 216, there is a circumferential passage 217,217 eachbeing in communication with said return line r through an axial bore bfashioned within said spool 213 to open endwise through said forwardportion 214 into the port 209.

The valve spool 213 is adapted to be moved axially between two positionswithin the valve chamber 204 responsive to fluid pressure entering theports 209 and 210, and acting on the respective end faces of the forwardand rearward portions 214 and 215. In one position, the diametricallyreduced portion 216 establishes communication between the feeder port206 and the port 205 for interconnecting the pilot line 207 with theline and in the other position between the feeder port 206, and the port205 for connecting the pilot line 207 to the line 135. Accordingly, bythe employment of pilot sequence valve V, the pilot fluid will bedirected to the master control valve M alternatively through lines 135and 135', respectively, for effecting the sequential extension of thefloor gate 33 and the ejector gate 39.

The rearward portion 215 of the spool valve 213 is formed with a pair ofspaced-apart circumferential grooves g,g for alternatively receivingspring-loaded ball detents, collectively designated 218 (FIG. 5) formaintaining said spool valve 213 ,in a preselected position. Since eachof the ball detents 218 are identical in construction, only one will bedescribed; it being understood that the other ball detents 218 operatein the same manner.

Said valve body 200 is furnished in its side wall 202 with a pluralityof circumferentially spaced-apart bores 219, each of which receive aball 220 which projects into the valve chamber 204 for reception withineither of said circumferential grooves g or g. Each bore 219 is formedwith a tapped counterbore 223 for threadedly receiving the shank 224 ofa lock screw 225; said shank 224 having an axial bore 226 therein forreceiving one end portion of a helical spring 227, the other end portionbearing against the related ball 220 for urging same into the selectedgroove g or g. Each lock screw 225 is provided with an enlarged head 228which is received within a recess 229 formed within a flat 230 machinedin the side wall 202 of the body 200. The recess 229 cooperates with thebore 219 to define a seat against which the head 228 abuts. Accordingly,the ball detents 218 will retain spool valve 213 in a predeterminedposition until the fluid pressure at one of the opposed ends at ports209 and 210 is sufficient to overcome the bias of the helical spring 227for urging the valve spool 213 into its other position.

MANUAL CONTROL VALVE C Conveniently provided on tractor 21 is a manualcon trol valve C comprising a body 300 having end walls 301, 301' and aside wall 302; there being a longitudinal bore 303 extending through theend wall 301", which bore 303 terminates spacedly from end wall 301.Provided for slidable reciprocal movement within the bore 303 is aplunger 304, of varying cross section, having a handle 305 on its outerend portion for use in the selective manipulation of the plunger 304into a desired position. The plunger 304 incorporates a pair ofspaced-apart heads 306,307, which are of the same diameter as that ofbore 303. Interconnecting the heads 306 and 307 is a diametricallyreduced portion 308 cooperating with the heads 306 and 307 and theadjacent wall of the bore 303 to define a fluid passage 309.

The side wall 302 of the body 301 is provided with ports 310,311,312 and313; the ports 310 and 311 being connected to feeder port 206 and port210, respectively, of pilot sequence valve V through said pilot line 207and conduits 211 and 212, respectively, and port 312 being connected bythe return line 314 to the pilot reservoir 208. The port 313- isconnected by line 315 to the discharge side of a pump 316, the intakeside of which is connected by a line 317 to the pilot reservoir 208. Itwill be observed that the port 313 is disposed axially between the ports310 and 311 so that the plunger 304 may be slidably moved within thebore 303 for establishing alternative communication between the ports313 and 310 and the ports 313 and 311 through said fluid passage 309.Additionally, the body 300 is provided with a fluid by-pass 318 havingports 319,319 opening into said bore 303 at opposed ends thereof.

The manual control valve C is adapted for movement into three positions;namely, a neutral position (not shown), a gate extended position (FIG.2), and a gate retracted position (FIG. 4). In the neutral position (notshown) the heads 306,307 block the ports 310,311, respectively, forprohibiting the entry of fluid from the pilot reservoir 208 to eitherthe pilot line 207 or the conduit 212.

In the gate extended position (FIG. 2) the plunger 304 is pulledoutwardly for-positioning said fluid passage 309 to establishcommunication between ports 313 and 310 for directing fluid from thepilot reservoir 208 to the feeder port 206 of the pilot sequence valve Vthrough the pilot line 207. Also, the port 311 is in communication withthe port 312 so that return flow of fluid from conduit 212 may bedirected through conduit 314 to the pilot fluid reservoir 208.

In the gate retracted position (FIG. 4) the plunger 304 is pushedinwardly for locating the fluid passage 309 within bore 303 to establishcommunication between the ports 313 and 311 so that fluid from the pilotfluid reservoir 208 will be directed through conduits 212 and 211, aswill be described. Additionally, communication is established betweenthe ports 310 and 319 and between ports 312 and 319' for permittingreturn flow from the pilot line 207 through by-pass 319 and the conduit314 to the pilot fluid reservoir 208.

OPERATION As mentioned hereinabove, a problem of the prior art elevatingscrapers was that the ejector gate and the FLOOR GATE EXTENSION In orderto extend the floor gate 33, the vehicle operator engages the handle 305of the manual control valve C and pulls same outwardly into its gateextended position (FIG. 2). Fluid from the pilot fluid reservoir 208 ispumped by the pump 316 through the conduits 317 and 315 into port 313 ofmanual control valve C, where fluid is passed through the fluid passage309, port 310 and pilot line 207 to the feeder port 206 of the pilotsequence valve V. The spool 213 of the pilot sequence valve V ispositioned within the valve chamber 204 so that feeder port 206 and theport 205 are in communication through the diametrically reduced portion216 so that fluid is passed into the conduit 135 and the upper fluidhousing 112. The fluid impinges upon the upper end portion 107 of thespool 106 for urging same downwardly into its said gate extendedposition (FIG. 2), thereby establishing communication between ports 121and 122. It will be observed that any fluid contained in said lowerfluid housing 113 will be directed to the pilot fluid reservoir 208through conduits 231,212 and return line 314.

Fluid from the reservoir 126 is pumped by the pump 124 through theconduits 125 and 123 into the recess 119 for direction through theconduit 54 into the port 53 of fluid responsive cylinder 38 forimpingement against piston head 49 to extend the piston 37 and the floorgate 33. Upon upward extension of the piston head 49, the fluid on theupward side thereof is forced through the port 50, branch line 51,conduit 52, upper fluid passage 114, by-pass 131, lower fluid passage 115 and return lines 128 and 129 for return flow to the reservoir 126.

EJECTOR GATE EXTENSION When floor gate 33 has been fully extended (FIG.3), the piston head 49 opens port 55 for permitting the fluid within thecylinder compartment 48 to enter conduit 56. Fluid is directed throughthe conduit 56 into the port 209 for impinging against the end wall ofthe forward portion 214 of spool 213. When the pressure within the valvechamber 204 is sufficient to overcome the inherent bias of the balldetents 218, the spool 213 will shift axially for closing the port 205and opening the port 205 for establishing communication between the port205 and the feeder port 206. Fluid from pilot line 207 is then directedthrough the diametrically reduced portion 216 into conduit for deliveryto the upper fluid housing 112' of spool valve 100'. When the pressurein line 135 is relieved, upon shifting of the spool 213, through saidcircumferential passage 217, bore b and return line r to the pilot fluidreservoir 208, the spool 106 of the spool valve 100 will return to itsneutral position (FIg. 3). Fluid from the reservoir 126 will be directedthrough conduit 123, recess 119 and groove 116, passage 117, and line118 for transmittal to the spool valve 100. The fluid pressure in upperfluid housing 112' of spool valve 100' impinges against the upperportion 107 for urging spool 106' downwardly into its gate extendedposition wherein communication is established between the ports 121 and122 through the recess 119'. It will be observed that any fluidcontained in the lower fluid housing 113' will be directed to the pilotfluid reservoir 208 through the conduits 231', 212 and the return line314.

Fluid entering through the line 118 will be directed through the conduit62 into the port 61 of the fluid responsive cylinder 45 for impingingagainst the piston head 59 thereby urging same outwardly of said fluidresponsive cylinder 45. The fluid in the compartment 58 on the upwardside of the piston head 59 is directed through the port 60, branch line51, conduits 52 and 133 into the upper fluid passage 114' by-pass 131and the lower fluid passage 115' into the return line 129 for returnflow to the reservoir 126.

FLOOR GATE AND EJECTOR GATE RETRACTION When both the floor gate 33 andthe ejector gate 39 are in fully extended position and it is desired toreturn same to their retracted position, the operator pushes inwardly onthe plunger handle 305 of the manual control valve C (FIG. 4). Fluidfrom the pilot fluid reservoir 208 is pumped by the pump 316 through thelines 317 and 315 into the port 313 for direction through the fluidpassage 309 and the port 311 for entry into the conduits 212 and 211.The fluid passing through the conduit 211 is directed to the port 210 ofthe pilot sequence valve V for impinging against the end wall of therearward portion 215 for urging the spool 313 axially within valvechamber 204. The movement of spool 213 is momentarily retained by thelocking engagement of the ball detents 218 within groove g. Meanwhile,fluid in conduit 212 is directed through the branch lines 231,231 to thelower fluid housing 113,113 wherein the fluid impinges on the lowerportion 108,108 of each spool 106,106 for urging same into its gateretracted position (FIG. 4). As the spool 106 is moved upwardly withinthe bore 105 the fluid within upper fluid housing 112 is directedthrough the conduit 135 through the port 205, diametrically reducedportion 216 and feeder port 206 for return through the pilot line 207,port 310, and thence into port 319, by-pass 318, port 319' and port 312for return flow through return line 314 to the pilot fluid reservoir208. When the pressure within the valve chamber 204 is sufficient toovercome said ball detent 218 the spool 213 axially shifts therebyblocking the port 205 and establishing communication between the port 25and the feeder port 206 so that the fluid within the upper fluid housing112 may be returned through the conduit 135, the pilot line 207, by-pass318 and return line 314 to the pilot fluid reservoir 208. I

With both spools 106,106 in their gate retracted position, fluid fromthe reservoir 126 is pumped by the pump 124 through the conduit 123,recess 119, conduit 52 for direction into the branch line 51 where fluidenters simultaneously through ports 50 and 60 into the compartments 48and 58, respectively, of the fluid responsive cylinders 38 and 45,respectively. The fluid impinges upon the piston heads 49 and 59,respectively, for urging same into a retracted position. The fluid onthe downward side of piston head 49 is directed through port 53, conduit54 into the lower fluid passage 115, return lines 128 and 129 to thereservoir 126; and the fluid on the downward side of piston head 59,through the port 61, conduit 62 and lower fluid passage 115' of thespool valve 101' for return through return line 129 into the reservoir126.

Thus, by the provision of the novel pilot sequence valve V within theflow control system for the elevating scraper 20 and its discreteconnection with the fluid responsive cylinder 38 of the floor gate .33,the sequential extension of floor gate 33 and ejector gate 39 is assuredat all times.

Having thus described my invention, what I claim and desire to obtainLetters Patent for is:

1. A fluid system for sequentially operating first and secondwork-performing elements comprising:

a first source of fluid;

first conduit means connecting said first source of fluid to each ofsaid first and second workperforming elements;

first valve means including a first valve member presented within saidfirst conduit means for directing fluid from said first source of fluidto said first and second work-performing elements;

said first valve member being adapted for movement into at least twopositions wherein:

a. A first position, fluid is directed to said first work-performingelement; and

b. In a second position, fluid is directed to said secondwork-performing element;

a second source of fluid;

second conduit means communicating said second source of fluid with thefirst valve member of said valve means;

' valve control means comprising second valve means disposed within saidsecond conduit means for selectively directing fluid from said secondsource of fluid to said first valve means for moving said first valvemember initially into said first position, and then sequentially intosaid second position.

2. A fluid system as defined in claim 1 and further characterized by:

said second valve means comprising a body having a chamber;

a second valve member positioned within said chamber for reciprocalmovement between first and second positions;

means adjacent the opposed ends of said chamber for urging said secondvalve member into said first and said second positions;

wherein said first position, the fluid from said second source of fluidis directed to said first valve means for effecting movement of thefirst valve member into its said first position;

and in said second position fluid from said second source of fluid isdirected to said first valve means for effecting movement of said firstvalve member into its second position.

3. A fluid system as defined in claim 2 and further characterized by:

said first work-performing element having a port;

a fluid line interconnecting one end portion of the chamber of said bodywith the port of said first work-performing element;

said port being positioned on said first workperforming element so thatwhen the latter is in a fully-extended position, fluid will be directedthrough said fluid line for urging said second valve member into itssaid second position.

4. A fluid system as defined in claim 2 and further characterized by:

detent means provided in the body of said second valve means forprojection into said valve chamber;

said second valve member having a pair of spaced apart recesses forreceiving said detent means;

said detent means being engaged within one of said recesses when saidsecond valve member is in said first position, and in the other of saidrecesses when in said second position.

v 11 12 5. A fluid system as defined in claim 2 and furthercharacterized by: characterized by: I a second fluid lineinterconnecting said second a fluid line interconnecting said secondsource of source of fluid to the other end portion of the fluid to oneend portion of the chamber of said chamber of said second valve meansremote from body; 5 that of said first fluid line connection; thirdvalve means within said fluid line for directing third valve meanswithin said second fluid line for difluid from said sedond source offluid to said secrecting fluid from said second source of fluid to ondvalve means for urging said second valve memsaid second valve means forurging said second ber into said first position. valve member into saidfirst position. 6. A fluid system as defined in claim 3 and further

1. A fluid system for sequentially operating first and secondwork-performing elements comprising: a first source of fluid; firstconduit means connecting said first source of fluid to each of saidfirst and second work-performing elements; first valve means including afirst valve member presented within said first conduit means fordirecting fluid from said first source of fluid to said first and secondwork-performing elements; said first valve member being adapted formovement into at least two positions wherein: a. A first position, fluidis directed to said first workperforming element; and b. In a secondposition, fluid is directed to said second workperforming element; asecond source of fluid; second conduit means communicating said secondsource of fluid with the first valve member of said valve means; valvecontrol means comprising second valve means disposed within said secondconduit means for selectively directing fluid from said second source offluid to said first valve means for moving said first valve memberinitially into said first position, and then sequentially into saidsecond position.
 2. A fluid system as defined in claim 1 and furthercharacterized by: said second valve means comprising a body having achamber; a second valve member positioned within said chamber forreciprocal movement between first and second positions; means adjacentthe opposed ends of said chamber for urging said second valve memberinto said first and said second positions; wherein said first position,the fluid from said second source of fluid is directed to said firstvalve means for effecting movement of the first valve member into itssaid first position; and in said second position fluid from said secondsource of fluid is directed to said first valve means for effectingmovement of said first valve member into its second position.
 3. A fluidsystem as defined in claim 2 and further characterized by: said firstwork-performing element having a port; a fluid line interconnecting oneend portion of the chamber of said body with the port of said firstwork-performing element; said port being positioned on said firstwork-performing element so that when the latter is in a fully-extendedposition, fluid will be directed through said fluid line for urging saidsecond valve member into its said second position.
 4. A fluid system asdefined in claim 2 and further characterized by: detent means providedin the body of said second valve means for projection into said valvechamber; said second valve member having a pair of spaced apart recessesfor receiving said detent means; said detent means being engaged withinone of said recesses when said second valve member is in said firstposition, and in the other of said recesses when in said secondposition.
 5. A fluid system as defined in claim 2 and furthercharacterized by: a fluid line interconnecting said second source offluid to one end portion of the chamber of said body; third valve meanswithin said fluid line for directing fluid from said sedond source offluid to said second valve means for urging said second valve memberinto said first position.
 6. A fluid system as defined in claim 3 andfurther characterized by: a second fluid line interconnecting saidsecond source of fluid to the other end portion of the chamber of saidsecond valve means remote from that of said first fluid line connection;third valve means within said second fluid line for directing fluid fromsaid second source of fluid to said secOnd valve means for urging saidsecond valve member into said first position.